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FGM-148 Javelin
The FGM-148 Javelin is a crew-served, infrared-guided fire-and-forget anti-tank missile launcher developed by the United States. Javelin is typically issued to a team of 2-3 soldiers, with one acting as the gunner and the remainder ammo carriers and spotters. History The Javelin was jointly developed by Texas Instruments and Martin Marietta as their submission to the 1983 AAWS-M (Advanced Antitank Weapon System-Medium, pronounced "awesome") program: this was a US Army requirement for an infantry guided missile system to replace the mediocre and obsolete M47 Dragon. The first proof-of-principle weapons were produced in 1986, with the US Army evaluating three competing designs: Ford Aerospace's LOSBR (line of sight beam riding) weapon, Hughes Aircraft Missile System Group's wire-guided system using imaging infrared and a fiber-optic datalink, and Texas Instruments' wireless fire-and-forget system using imaging infrared guidance. The latter system would ultimately become the Javelin. The first test-flight of a production Javelin missile occurred in 1991, with the first firing from a complete launcher in 1993. Low-level production for final testing began in 1994, with the missile first being deployed with US Army units in 1996. Design Javelin is a system consisting of two parts, the Launch Tube Assembly (LTA) and Command Launch Unit (CLU). The LTA is disposable, while the CLU is re-usable and is removed from the expended LTA after firing. The LTA consists of a single missile encased in a fiberglass tube with a permanently attached rear shock absorber and a detachable front shock absorber/end cap. The LTA also incorporates a shoulder rest pad, and comes fitted with a carrying strap and folding carry handle. The LTA mounts a battery coolant unit (BCU). This consists of a non-rechargeable lithium-ion power cell and a reservoir of liquid argon, and can power the missile and cool the seeker for 4 minutes once activated. If the missile is not fired within this time window, the expended BCU can be detached from the tube and replaced with a new one. Collectively, the LTA, encased missile and BCU are referred to as the "round." The CLU module uses a non-rechargeable lithium sulfur dioxide battery in combat or a rechargeable nickel metal hydride training battery to supply it with power, and incorporates the fire control computer, all controls for firing the missile on a pair of handgrips, and an integral day/night sight with an electronic cryocooler for the night optics. The CLU can function as a surveillance device without a missile fitted. Both modules feature electronic built-in test (BIT) features which perform automated function testing, continuously in the CLU and when attached for the missile. CLU functionality The CLU has day and night sighting modes and two field of view options, allowing for a 4x magnification wide field of view (WFOV) when the gunner is scanning for targets, and a 12x magnification narrow field of view (NFOV) to focus on a target after it is located. The day mode is a simple optical sight and can be used even if the CLU is switched off. The night mode uses a passive infrared camera with a lens cover provided for when it is not in use. When connected to an activated missile there is a third option available, Seeker FOV, which switches to a 9x magnification thermal view from the seeker of the missile itself. Since the night vision sight (NVS) uses an electronic cooler rather than gas cartridges, there is a fairly substantial waiting time of between 30 seconds and 3.5 minutes (normally around 2.5 minutes) between setting the CLU power switch to NIGHT mode and the night vision mode becoming available, depending on ambient temperature. This also means the CLU's battery life varies depending on the ambient temperature, from 4 hours at ideal temperature to as little as half an hour above 49 °C (120 °F). The controls for the CLU are located on the two handgrips, grouped into sighting controls on the left grip and fire controls on the right. A four-position hat switch on the right handgrip serves two functions depending on the view mode: in night-vision mode it is the brightness and contrast adjustment, while in seeker view mode it adjusts the tracking gates that the missile uses to distinguish its target. Around the perimeter of the rectangular viewing portion of the M98A1 CLU are a series of indicator icons, four at the top and bottom and two at the sides. The icons at the top and right are green and display setting information, the icons at the lower-right and top-left are amber and indicate status issues (the lower-right can also turn red), and the remainder are red and indicate either emergency conditions or failures. Clockwise from the top-left, they are: * DAY: indicates the power switch is in either the DAY or NIGHT position. * WFOV: indicates wide field of view setting. Flashes if the WFOV mode has reached its focus limit. * NFOV: indicates narrow field of view setting. Flashes if the NFOV mode has reached its focus limit. * SEEK: indicates seeker view setting. * TOP: indicates top-attack mode selected. * DIR: indicates direct attack mode selected. * FLTR: "filter," indicates the NVS filter is active. * MISSILE NOT READY: solid amber indicates the missile is not ready to fire: flight information not uploaded, BIT incomplete, or seeker not cooled. Flashing amber indicates the missile electronics are overheating, and will automatically shut down in 30 seconds. Solid red indicates the missile has overheated. * MISSILE BIT FAILURE: steady light indicates the missile has failed one or more BITs or failed to initiate a BIT when commanded by the CLU (communication failure), flashing indicates a misfire. * HANGFIRE: indicates a launch failure. * BCU indicator: starts flashing when the BCU has 30 seconds of power and gas remaining, solid red indicates BCU expended. * CLU BATTERY: lights up when the CLU's battery power is 5 minutes or less. * CLU BIT FAILURE: indicates the CLU has failed one or more BITs, or has failed to send data to the missile. May also come on if the CLU battery is depleted or failing. * NVS NOT COOL: indicates the CLU has been set to night mode but the night optics are not cold enough to function. At the bottom of the display is an "iron sight" of sorts, a set of physical rangefinding stadia that appear in all views and whether the CLU is on or off. Additional white digital stadia lines and an aiming reticle are present in the WFOV and NFOV modes when the CLU in night vision mode: WFOV uses a partial box reticle which denotes the NFOV field of view, NFOV a partial crosshair which denotes the default area of the tracking gates in SEEK mode. The M98A2 CLU is an improved variant with a better video display: this version does not use physical lights as indicators, rather having them be parts of the video display, and has a much more detailed set of status indicators and menus: the only physical indicators are two LEDs at the bottom of the display, one a power light and the other a CLU BIT test light. A modernised CLU was developed in 2013: this adds integration with the US Military's Far Target Location (FTL) system, allowing the CLU to be used as a sighting unit for other weapons. It is 70% smaller, 40% lighter and has a 50% improvement in battery life over the current CLU. It adds a modern high-definition display, a long-wave IR sensor, a 5 megapixel camera and an integrated laser rangefinder/designator. Firing procedure Javelin is usually fired with the gunner in a seated or kneeling position, though it is possible to fire the weapon while standing with suitable support, or even while prone if procedure is properly followed. The loading procedure begins by removing the protective cover from the CLU interface connector and mating the LTA with the CLU. The end cap of the LTA is then removed by pulling out a locking pin, releasing the latch and sliding it off. This exposes the missile seeker, so care must be taken following this to avoid damaging it. The system is now able to be fired. Prior to firing, the gunner first "sights" along the top of the LTA to gauge the missile's initial trajectory and ensure the missile will not collide with obstructions such as trees or power lines on launching. Once a suitable target is located and the line of fire checked for obstructions, the seeker trigger on the left handgrip is pulled and held. This activates the BCU and provides power and coolant to the missile's seeker, with a ten-second delay before the seeker is cooled to operational temperature. Once this is achieved, flashing tracking gates will appear in the CLU's sight view. These are manually adjusted by the gunner using the hat switch on the right grip to frame the target's hull (the turret, if present, is disregarded), while placing the crosshair that appears in the sight directly over the target's center of mass. The crosshair will flash while the seeker is active, and both it and the tracking gates turn solid when a lock has been achieved. Javelin uses contrast to track its target, and so can lock on to targets that are either hotter or colder than their surroundings. Once a target is locked, the gunner pulls the firing trigger on the right handgrip. The missile cannot be fired without a lock, and the firing trigger does not work at all if the seeker trigger is not held. As with most weapons using standard NATO rocket propellant, gunners are advised to hold their breath just before firing and keep it held for a time afterwards: this is not for bracing, but because toxic elements are present in the exhaust plume. On firing the launch motor ignites, burning out inside the launch tube and propelling the missile around 4.6 meters (15 feet) from the launcher, at which point the main booster ignites and the missile begins a rapid climb as its autopilot activates. As the missile exits the tube its wings and fins pop out. The main booster burns out after the climb-out has completed, and the missile glides for the remainder of its flight time. Javelin has a backblast danger zone of 25m (82 feet) in a 60-degree arc to the rear of the launcher, with a "caution zone" extending out to 100m (328 feet). Guidelines for firing from an enclosure give minimum room dimensions as 15×12×7 feet (4.6×3.7×2.1 meters). After firing, the spent LTA is dismounted from the CLU: when time permits, it is destroyed in some expedient manner. Attack modes The missile's flight profile can be set by the operator to attack specific types of target: this is controlled by the switch marked ATTK SEL (attack select) on the right handgrip of the CLU. The default mode is "top attack," a mode designed to allow the missile to attack the weak upper surface of enemy armored vehicles. In this fire mode the missile rapidly ascends before nosing over and gliding down to its target at a steep angle. The climb out height is determined automatically by the missile's internal flight control software. Direct attack mode is an alternate flight profile which can only be selected after the missile's seeker has cooled down and before lock-on. In direct attack mode the missile performs a much shorter climb-out and flies directly at the target, attempting to impact the side of it. This profile is used against targets with protective cover above, bunker firing slits, and is also effective against hovering helicopters. Ammunition Javelin's missile is 110cm (43 in) long and weighs 11.8kg (26 lbs) separated from the tube, of which 8.4 kg (18.5 lbs) is the warhead in the tandem-charge HEAT version. The warhead is impact fuzed. The LTA tube that contains the missile is 142mm in diameter, while the missile is 127mm (5in). There are two main missile variants: the standard HEAT warhead, and the currently under development Multi-Purpose Warhead (MPWH). The standard warhead is a tandem-charge designed to defeat modern reactive tank armor by using a precursor warhead to set it off prematurely, with a two-layer molybdenum liner for the precursor charge and a copper liner for the main charge: it is rated as capable of penetrating 600-800mm of rolled homogeneous steel. MPWH adds a fragmenting steel warhead case designed to improve the weapon's performance against soft targets. Internally the missile has three main subdivisions: at the front is the guidance section consisting of the seeker head, followed by the guidance electronics. The mid-body section includes the main warhead, electronic safe, arm and fire (ESAF) systems, and the flip-out wings. Finally, the propulsion section contains the launch motor, flight motor, flip-out control fins and thrust-vectoring control vanes, and the missile's integral thermal battery. The precursor warhead is mounted inside the guidance electronics section, while the contact switches that detonate the two warheads are in the seeker head. The propulsion system is designed with an emergency venting system to prevent a tube explosion if the pressure in the motor grows too high (for example, if the missile sticks in the tube). High pressures will open channels allowing the direction of thrust to reverse, and the propulsion section will shear off from the rest of the missile and fire itself out of the back of the LTA. References *FM 2-22.37 "Javelin - Close Combat Missile System," Headquarters, Department of the Army, March 2008 Category:Anti-tank missiles Category:Fire-and-forget weapons Category:Missile launchers